The subject invention is an improvement on the invention disclosed and claimed in commonly owned U.S. Pat. No. 3,767,064, issued Oct. 23, 1973, to David Edward Lutz and entitled "Traveling Walking Beam Conveyor." Apparatuses of this type are used, for example, to move strings of palletized loads into and out of the backs of trucks or trailers from and to a loading dock. Since the standard height of the space under pallets is only four inches, and since the strings of pallets that such apparatuses move may be many feet long, such apparatuses must be extremely low relative to their lengths. Additionally, since the pallets are often heavily loaded and since the apparatuses must be capable of carrying several (e.g., eight) such pallets in such a string, such apparatuses must be extremely sturdy. Moreover, since such apparatuses have to be capable both of moving under a string of palletized loads without moving the pallet and of carrying the pallets, such apparatuses have to be capable of moving in both of two different modes (referred to herein as "the crawl mode" and "the walk mode").
Although not essential to such apparatuses, it is highly desirable that they be capable of indexing a string of pallets forward as each successive pallet is removed, one-at-a-time from the front end of the apparatus. Similarly, although not essential to such apparatuses, it is highly desirable that they be capable of moving laterally and of pivoting about either end in order to compensate for inadvertent cocking taking place during normal use.